Composite building panels, such as gypsum wallboard, are well known for interior wall and ceiling construction. Some of the main advantages of wallboard over other materials is that wallboard is less expensive, a fire retardant and easy to work with in construction applications. In construction, wallboard is typically secured to wood or metal supports of framed walls and ceilings using fasteners such as nails or screws. Because wallboard is relatively heavy, it must be strong enough to prevent the fasteners from pulling through the wallboard and causing the wallboard to loosen or fall away from the supports.
Nail pull is an industry measure of the amount of force required for wallboard to be pulled away from the associated support and over the head of such a fastener. Preferable nail pull values for wallboard are in the approximate range of between 65-85 pounds of force. Nail pull is a measure of a combination of the wallboard core strength, the face paper strength and the bond between the face paper and the core. Nail pull tests are performed in accordance with the American Society for Testing Materials (ASTM) standard C473-00 and utilize a machine that pulls on a head of a fastener inserted in the wallboard to determine the maximum force required to pull the fastener head through the wallboard. Because the nail pull value is an important measure of wallboard strength, minimum required nail pull values have been established for wallboard. Accordingly, manufacturers produce wallboard that meets or exceeds the minimum required nail pull values.
To ensure that wallboard meets the required nail pull values, conventional wallboard manufacturers adjust the structural parameters of the wallboard. Specifically, manufacturers typically adjust the face paper weight of wallboard having a known core strength value to meet the required nail pull value. During manufacturing, wallboard is tested to determine if it meets the required nail pull value. If the tested nail pull value of the wallboard is less than the required nail pull value, manufacturers increase the face paper weight on the wallboard. This process is repeated until the required nail pull value is met.
Such a process is inaccurate and commonly causes the tested nail pull values to exceed the required nail pull values due to excess face paper weight added to the wallboard. Also, the excess face paper adds weight to wallboard and thereby increases manufacturing and shipping costs of wallboard. Further, there is the likelihood of wasting time and material until the desired nail pull values are achieved on the wallboard production line.
Thus, there is a need for an improved technique of adjusting wallboard manufacturing systems to produce wallboard that meets specified nail pull values.